314 Trans. Acad. Sci. of St. Louis. 



neck of the archegouium. — 2-3, Successive sections of an archegonium. 

 Tiie spermatozoids a and b are seen entering blunt end first. In Fig. 3 

 a spermatozoid is seen in the depression in the surface of the egg-cell. — 

 4-5, Sections of another archegonium. The spermatozoid/ is seen entering 

 the egg- cytoplasm; s isa spermatozoid in the neck of the archegonium. c 

 is the cytoplasmic anterior end. c' same for /turned backward.— 4a, A 

 spermatozoid which lay in the mouth of an archegonium, c its cytoplasmic 

 anterior end already disconnected. — 6-8, Successive sections of an egg; s, 

 spermatozoid entering. — 9, Vertical longitudinal section of archegonium 

 with a spermatozoid lying in the neck and another entering the egg. — 

 10, Fertilization of the egg. v, Depression in surface of egg appearing as 

 a hole in section with the spermatozoid / partially coiled ia it. — 11, Fer- 

 tilization of the egg; spermatozoid entering as before. — 12, Fertilization of 

 the egg; spermatozoid entering the egg at its tip. — 13-13a, Entrance of 

 sperm-nucleus into egg-nucleus, a-b cytoplasmic envelope of nucleus lying 

 outside egg-nucleus and extending into it at b. Fig. 13a is a diagram of 

 Fig. 13, turned 90 degrees on the axis x-y. — 14-16, Fertilized egg in suc- 

 cessive sections, d, a conical depression in surface of nucleus; c, cytoplas- 

 mic anterior end left outside the egg-nucleus. — 17, 18, and 18a, two suc- 

 cessive sections of a fertilized egg and a diagram of the same egg viewed 

 from above; c, c' the cytoplasmic envelope of the sperm nucleus left outside 

 the egg nucleus. — 19-20, Two sections of another fertilized egg, showing 

 the cytoplasmic sheath outside the nucleus in Fig. 19 and the sperm-nucleus 

 inside the egg-nucleus in Fig. 20. — 21-22, Fertilized eggs showing unchanged 

 sperm-nuclei.— 23-25, Successive sections of a fertilized egg.— 26, Fertilized 

 egg where the disorganization of the sperm-nucleus has gone much farther. — 

 27-41, Stages in the development of the spermatozoid. —42, Cross-section 

 of ripe spermatozoid. — 43, Diagram of archegonium in vertical longitudinal 

 section. — 44-48, Diagrams of the egg-cell. — 49, Cross-section of prothal- 

 Hum showing two embryos in the same calyptra; c, cotyledon; F, foot; r, 

 root; s, stem. 



Issued August 4, 1899. 



